In current storage networks, and particularly storage networks including geographically distributed directors (or nodes) and storage resources, it is desirable to maintain data consistency throughout so that different hosts in different locations see the same data. An example of a system for providing distributed data coherence is described in U.S. Pat. No. 7,975,018 to Unrau et al., entitled “Systems and Methods for Providing Distributed Cache Coherency,” which is incorporated herein by reference. Other systems and techniques for managing and sharing storage array functions among multiple storage groups in a storage network are described, for example, in U.S. Pat. No. 7,266,706 to Brown et al. entitled “Methods and Systems for Implementing Shared Disk Array Management Functions,” which is incorporated herein by reference.
Data transfer among storage devices, including transfers for data replication or mirroring functions, may involve various data synchronization processing and techniques to provide reliable protection copies of data among a source site and a destination site. In synchronous transfers, data may be transmitted to a remote site and an acknowledgement of a successful write is transmitted synchronously with the completion thereof. In asynchronous transfers, a data transfer process may be initiated and a data write may be acknowledged before the data is actually transferred to directors at the remote site. Asynchronous transfers may occur in connection with sites located geographically distant from each other. Coordinating and controlling the sharing of resources distributed among these different storage nodes may, in many cases, be difficult or problematic using known technologies.
Accordingly, it is desirable to provide an effective and efficient system to address issues like that noted above for a distributed system.